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Which OS for a PDP-11/84

m_thompson

m_thompson

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I am assembling a PDP-11/84 and am wondering what OS I should install. I will probably a CMD disk controller with SCSI disks emulating RA81s, so disk space will not be a problem. It will have 1MB or 2MB of RAM depending on which boards I can find. I have a DEUNA Ethernet board set that I can install. I will install an RL02 for a removable disk. There is lots of room in the chassis for more controllers.

I was thinking of RSTS/E, Ultrix-11, or V2.11 UNIX. The plan is to build a disk image using SIMH and then transfer the disk image over a serial port. Using SIMH seems simpler than trying to get a TU80 working and making an installation tape.
 
On mine I have used BSD 2.11 and RSTS/E. Used a Linux box with Simh to create the RA92 images. And since I have an Adaptec controller in it I can simply DD the image to the drive or to the SCSI2SD. Mine has a UC17 for the SCSI controller. I had tried to use VTServer a few times to create the BSD image, but one of the files is too big. And trying to patch VTServer just didn't work. I believe I never updated the pdp-11 code that runs on the 11/84 for that. But never did the directions even point to do that. Yeah, I don't think you want to boot a real tape, but it would be neat to do it I suppose.
 
I have installed RSTS/E 10.1 and 2.11BSD on KDJ11 systems from tape drives a few times just for the experience of doing it. It really isn't too bad to do it once or twice. I have used a Pertec interface Fujitsu M2444AC 9-track drive, and a SCSI interface Exabyte 8200 8mm drive.

I have never tried using VTServer to transfer a disk image through a serial port connection. That sounds a lot more painful than installing from a tape drive. As already mentioned, creating a disk image using SIMH and then using DD to dump that image to a physical SCSI device is always going to be the quickest method.
 
Well, back then I most likely did not have the UC17 so my only choice was to use VTServer. It works quite well for any file up to 32MB. But the final file is well over that. There is a patch to fix it but it only talks about patching the VTServer side, not the pdp-11 side. Once started you can just walk away. It isn't the fastest thing at 9600. I don't remember if it worked at 115200 or not.
 
I have 2.11BSD on my 11/44 system with an Emulex UC17 UNIBUS SCSI disk controller, DEUNA ethernet interface, RX211/RX02, and DZ11 serial lines.

I originally did all the setup on SIMH, and then CYGWIN DD'ed the file over to a SCSI disk (2.1G seagate IIRC) that I mount on my old WinXP system that has an Adaptec SCSI controller.

The configuration and setup process, and a 2.11BSD image, are all documented here: https://www.ak6dn.com/PDP-11/2.11BSD/ along with a SIMH console log file.

Don
 
Thanks for the thoughts. I could use one of my Sun systems to DD and image to a drive.

I need to see if the CMD SCSI controller does anything interesting to the disk when it partitions a physical disk into multiple logical disks.

I am going to bring up the machine with just an RL02 disk, so VTServer should work nicely for that. Once the machine is reliable I can add the SCSI disks.

The CMD controller supports disks and tapes on the same SCSI bus, and then looks like two DEC controllers. I have a Sun badged HP 1/2" 9-track tape drive, so I could try a tape installation.
 
m_thompson said:
I am going to bring up the machine with just an RL02 disk, so VTServer should work nicely for that. Once the machine is reliable I can add the SCSI disks.
Click to expand...

One thing that I have found helpful when bringing up a system, or reconfiguring the hardware on an existing system, is to create an MSCP bootable XXDP 2.5 image and burn that to a CD-ROM. Then use that with SCSI controller and SCSI CD-ROM drive to boot XXDP to run diagnostics on everything and make sure those pass before going through a new OS installation process. Plextor SCSI CD-ROM drives with a 512-byte sector switch have worked well for this with CMD SCSI controllers.
 
I have some SCSI Toshiba CDROM drives from Sun systems that support the small sector size and Sun systems will boot from them. I imagine that the 11/84 would also boot from them. I will see if I can make a bootable XXDP CDROM.
 
There is an 11/84 waiting for me too. If you succeed on the xxdp cd-rom than I would love to receive an image too.

I hope to find a Emulex UC17 for a fair price.

Regards, Roland
 
It's been quite a while, but I was very happy using ZIP drives to move from SIMH to my 11/83 with RL02 drives. IDE or USB on the SIMH side (probably WinXP at the time?) and SCSI on the qbus. Don documents the BSD patch needed to accommodate the CMD controllers and Glen's site is very helpful for CMD/MTI ROMs and setup. I used NEC and Apple CD-ROMs to write bootable media before switching to the ZIP drives.
 
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